1. Technical Field
The present invention relates to a tobacco filter which is filled in a tobacco pipe or integrated in a cigarrette in order to remove harmful components such as tar and nicotine as well as carcinogens from tobacco smoke.
2. Prior Art
In recent years, harmful components of tabacco smoke are creating problems. Particle-phase components such as tar and nicotine have long been known to be the harmful substances, and in order to remove them, smoke filters have been integrated into cigarettes and filled into tobacco pipes. These filters use fibrous materials such as natural cellulose and acetate, or filtering materials of the continuous pneumatophore type. These materials can adsorb and remove tar and nicotine to some degree, but not sufficiently. Besides, they are not effective in removing harmful gas-phase components from the tobacco smoke.
Consequently, compound filters using the above-mentioned fibrous materials or other various filtering materials attached or filled with the activated charcoal are used to remove tar and nicotine as well as harmful components of gas phase. However, tar and nicotine still cannot be removed sufficiently, and in order to remove them sufficiently, a large quantity of the filtering material is required, which obstructs attempts to make a compact filter for use with tobacco pipes and cigarrettes. It also increases the resistance against smoke passage, resulting in the decreased enjoyment of smoking.
In addition, the activated charcoal is said to be insufficiently effective in removing the harmful gas-phase components, and actually cannot remove, in particular, carcinogens such as 3,4-benzopyrene at all.
In this circumstance, for the pupose of removing, in particular, the gas-phase carcinogens, a method was developed to attach lactic or egg protein, or a mixture thereof to the fibrous filtering materials (Japanese Patent Provisional Publication No. 73/19800). Although it is reported to have a certain effect of removing the carcinogens, it also has several disadvantages such as the decreased enjoyment of smoking because of the larger resistance against smoke passage, and the tendency to deterioration in the air at a room temperature, compared to the filters with no such protein attached to the filtering materials. Besides, the said protein itself does not provide a strong effect of removing the particle-phase components such as nicotine and tar, and therefore, cannot be expected to improve the effectiveness in removing the particle-phase components. By granulating the lactic protein, the problem of smoke pass resistance can be eased to some degree (Japanese Patent Provisional Publication No. 75/126899). In this case, however, the effectiveness in removing the harmful gas-phase components is affected in turn.
Another type of tobacco filter is also offered with biopolymer such as serum albumin and yeast nucleic acid filled into the cellulose filtering material. This type of filter can adsorb 3,4-benzopyrene, but still not sufficiently. And, since it may be deteriorated when kept in the air at a room temperature, care should be taken to keep it sealed until actually used, and to open it just before use. In addition, the said biopolymer itself does not have a high capability of removing the particle-phase components such as nicotine and tar, and therefore, cannot be expected to improve the effectiveness on these components.
Still another type of filter is that which has chlorella filled into or attached to the fibrous material. It is reported to be effective in adsorbing 3,4-benzopyrene. However, it also seems to have a tendency to deterioration, and chlorella itself does not have a sufficient effect in removing tar and nicotine.